1. Technical Field
The subject disclosure relates to minimally invasive surgical procedures and apparatus and, more particularly, to instruments and methods for performing heart valve replacement surgery.
2. Background of Related Art
The diagnosis and treatment of coronary disease and related conditions often requires repair or replacement of the valves located within the heart. Various factors, such as, for example, calcification, may result in the mitrial or aortic valves becoming impaired or functionally inoperative requiring replacement. Where replacement of a heart valve is required, in general, the dysfunctional valve is cut out and replaced with either an artificial, synthetic heart valve or a harvested porcine heart valve. The replacement valve is typically sutured in place of the original valve.
Access to the heart in a patient""s thoracic cavity is achieved by making a longitudinal incision in the chest. This procedure, referred to as a median stemotomy includes cutting through the sternum and forcing the two opposing halves of the rib cage to be spread apart allowing access to the thoracic cavity and thus the heart.
Suitable instruments for spreading and holding apart the rib cage are marketed by United States Surgical Corporation, Norwalk, Conn. These instruments include, for example, Mini-CABG* retractors and related accessories. The Mini-CABG* universal retractor includes a substantially planar base having an opening which can be positioned on the patient such that the opening overlies the incision at the operative site. Mini-CABG* retractors are slidably mounted on the base and are provided to spread apart the rib cage halves and engage and retract obstructing tissue. The base may also be provided with surgical instruments which can be used to stabilize or manipulate the heart during surgery.
Once access to the thoracic cavity has been achieved, surgery on the heart to effect valve replacement may be performed. During some procedures, the heart beat is arrested by infusion of a cardioplegic fluid, such as potassium chloride (KCl), to paralyze the myocardium while blood flow circulation is maintained through known heart bypass techniques. Alternatively, the heart is allowed to beat to maintain circulation, while a localized area of the heart, on which surgery is to be performed, is locally immobilized by various instruments.
The heart is incised and the defective valve is cut away leaving a surrounding area of locally tougher tissue. Known heart valve replacement techniques typically include individually passing sutures through the tough tissue by hand to form an array of sutures. Free ends of the sutures are extended out of the thoracic cavity and laid, spaced apart, on the patient""s body. The free ends of the sutures are then individually threaded through an edge around the circumference of the replacement valve or a supporting cuff. This is also typically accomplished by hand. Once all sutures have been run through the valve, all the sutures are pulled up taught and the valve is slid or xe2x80x9cparachutedxe2x80x9d down, by hand, into place adjacent the tough tissue. Thereafter, the replacement valve is secured in place using the sutures. Since the conventional heart valve replacement techniques are exclusively manual procedures, they are typically time consuming and difficult.
Where replacement is performed utilizing an artificial valve, hand held instruments in the form of a stick may be affixed to the valve and used to manipulate the replacement valve into place. The commercially available replacement valves are typically provided with a detachable holder structure which can be engaged by the hand tools.
While the above described procedures are sufficient to successfully secure a heart valve within the heart, they are particularly time consuming. A more suitable apparatus is desired for securing the heart valve in position without the time consuming procedure of passing and tying individual sutures through the valve.
Therefore, a need exists for apparatus and procedures of quickly and efficiently positioning and affixing artificial heart valves within the heart. In particular, an apparatus designed to apply staples which are configured to secure the heart valve to the surrounding tissue and eliminate the need for sutures is desired. The staples may be installed one at a time, or a plurality of staples may simultaneously pierce a cuff of the heart valve.
There are provided various embodiments of a surgical heart valve stapler and methods for installing a synthetic, artificial heart valve within a patient. A preferred embodiment of the surgical stapler for securing a prosthetic heart valve within a patient generally includes a first cylindrical portion for carrying at least one staple assembly on a distal end thereof A second cylindrical portion is positioned concentrically about the first cylindrical portion and has a camming arm on a distal end thereof, the camming arm being configured to cam the at least one staple assembly radially outward and drive the at least one staple assembly distally such that a first leg of the at least one staple assembly penetrates a cuff of the prosthetic heart valve and a second leg of the at least one staple assembly pierces a portion of heart tissue surrounding the prosthetic heart valve, as the second cylindrical portion is moved distally relative to the first cylindrical portion. A third cylindrical portion is positioned concentrically about the second cylindrical portion and has an anvil flange on a distal end thereof, the anvil flange being configured to crimp the second leg of the at least one staple assembly toward the first leg of the at least one staple assembly to secure the prosthetic heart valve to the surrounding heart tissue as the third cylindrical portion is moved relative to the second cylindrical portion.
Preferably, a plurality of staple assemblies are positioned adjacent a circumference of the distal end of the first cylindrical portion for securing the heart valve to the surrounding heart tissue. The surgical heart valve stapler may further include a fourth cylindrical portion concentrically positioned within the first cylindrical portion for removably engaging a heart valve holder. Additionally, the surgical stapler for securing a prosthetic heart valve within a patient may also include a cylindrical shield portion concentrically interposed the second cylindrical portion and the third cylindrical portion, the cylindrical shield portion dimensioned and configured to shield the at least one staple assembly prior to insertion thereof into the heart valve and heart tissue.
A method of installing a heart valve within a patient is also provided which includes the steps of accessing a site within a heart from which a natural heart valve has been removed; lowering a prosthetic heart valve into position within the site in the heart; positioning a surgical stapler having at least one staple assembly removably held on a distal end thereof adjacent the prosthetic heart valve within the site in the heart; driving a first leg of the at least one staple assembly through a peripheral cuff of the prosthetic heart valve; and crimping a second leg of the at least one staple assembly in a direction toward the first leg such that the second leg pierces a portion of heart tissue surrounding the prosthetic heart valve, thereby securing the prosthetic heart valve to the surrounding heart tissue. The prosthetic heart valve is preferably removably mounted on a distal end of the surgical stapler such that the lowering step and the positioning step are performed simultaneously.
The crimping step in the above method is preferably performed by causing an anvil cylinder disposed on an outer periphery of the surgical stapler to move distally such that a circumferential flange on a distal end of the anvil cylinder crimps the second leg of the at least one staple assembly in a direction toward the first leg. Additionally, the driving step is preferably performed by causing a cylinder within the surgical stapler, having a camming arm on a distal end thereof, to move distally such that the camming arm cams the at least on staple assembly radially outward and drives the at least one staple assembly distally such that a first leg of the at least one staple assembly penetrates a cuff of the prosthetic heart valve and a second leg of the at least one staple assembly pierces a portion of heart tissue surrounding the prosthetic heart valve.